Fluid drainage catheters are known in the art. A class of catheters now commonly known as “Blake drains” were initially described in U.S. Pat. Nos. 4,398,910 and 4,465,481 to Blake et al., the entire contents of both of which are incorporated by reference herein. The Blake patents disclose wound drain catheters that include a flexible drain portion that is placed in a patient's body and in fluidic communication with a wound, and an outflow tube that exits the patient's body and connects to a suction device that draws fluid from the wound via the drain portion and the outflow tube. The Blake patents point to the deficiencies of perforated drain portions such as were previously known at that time, that included a length of tubing perforated by forming spaced apertures through the tubing wall. According to the Blake patents, one major problem with such perforated drains is that wound debris, such as clots, may block the apertures. Additionally, tissue may grow into the apertures, which not only may block the apertures, but also may make it difficult to remove the drain at a later time.
FIGS. 1A-1E, which have been adapted from U.S. Pat. No. 4,465,481, illustrate an exemplary embodiment of a “Blake drain” that includes longitudinal slits intended to overcome the deficiencies of perforated drains. Specifically, catheter 111 illustrated in perspective view in FIG. 1A, and in greater detail in 1B, includes a single continuous elongate member 115, which includes a drain segment 131, a second segment 151, called the transition tube segment, and a third segment 171, called the extension tube segment.
FIG. 1C illustrates a cross section of drain segment 131 along line 1C-1C in FIG. 1B. Drain segment 131 includes central core portion 133 with T-shaped members 137 projecting therefrom. T-shaped members 137 cooperate to define longitudinal flutes, lumens, or channels 136 that communicate with the environment surrounding the drain segment through grooves 135. FIG. 1D illustrates a cross section of transition tube segment 151 along line 1D-1D in FIG. 1B. Transition tube segment 151 includes core portion 153, which is colinear with core portion 133 of drain segment 131. Each of strut portions 155 projecting from core portion 153 is colinear with a corresponding T-shaped portion 137 of drain segment 131. The inner surface of tubular portion 159 is connected to the ends of the strut portions 155 so the tubular portion 159 and the strut portions 155 cooperate to form enclosed longitudinal channels 156. Each of the channels 156 communicates a corresponding lumen 136 of drain segment 131. FIG. 1E illustrates a cross section of extension tube segment 171 along line 1E-1E in FIG. 1B. Extension tube segment 171 includes tubular portion 177 defining internal longitudinal cavity 175. Tubular portion 177 is a continuation of tubular portion 159 so that cavity 175 communicates with all of the channels 156 of the transition tube segment 151.
As disclosed in U.S. Pat. No. 4,398,910, such a longitudinally fluted drain, rather than a perforated drain, is advantageous for a number of reasons. For example, a fluted wound drain has an increased tissue contact drainage area, increased luminal flow drainage area, and an increased cross-sectional area as compared to a perforated drain, resulting in increased fluidic throughput and increased strength. Moreover, the fluted configuration reduces the risk that tissue growth will inhibit removal of the drain.
The fluted wound drains disclosed in the Blake patents have been modified so as to enhance their suitability for certain purposes. For example, U.S. Pat. No. 6,976,973 to Ruddell et al. discloses a dual-lumen catheter for peritoneal dialysis that includes an “inflow” lumen allowing fluid to flow from outside the patient, through the catheter, and into the patient, and an “outflow” lumen allowing fluid to flow from the peritoneal cavity, through the catheter, and out of the patient. The outflow lumen may include a plurality of perforations, or alternatively a plurality of elongated slots through which fluid may flow out of the patient's body and a plurality of septa that partition the lumen. One such outflow lumen disclosed by Ruddell includes four slots and four septa, and appears generally similar to the fluted wound drain illustrated in FIGS. 1A-1E. FIG. 1F, which has been adapted from Ruddell, illustrates an alternative outflow lumen 88, which includes slots 80 on one side of a tube, a plurality of septa 82 defining lumens 86, an enclosed lumen 90 that may be part of the outflow lumen or party of the inflow lumen, and a radiopaque stripe 54. Ruddell discloses that slots 80 alternatively may be opposite from the radiopaque stripe (not shown here).
Although the fluted wound drains disclosed in the Blake patents and the peritoneal dialysis catheters disclosed by Ruddell may be partially implanted into a patient, both designs may have shortcomings rendering them unsuitable for long-term use, particularly within the peritoneal cavity. For example, slits 135 illustrated in FIG. 1B are equally susceptible to blockage as one another, as are slits 80 illustrated in FIG. 1F. In particular, if a wound drain or catheter having such slits is implanted in the peritoneum and a given portion of the patient's intestine drapes over the catheter, fluid flow through multiple of the slits potentially may be blocked simultaneously. Additionally, the catheter potentially may become ensnared in the greater omentum or the lesser omentum, which again may potentially block fluid flow through multiple of the slits simultaneously.
Accordingly, what is needed is a fluid drainage catheter with enhanced resistance to blockage.